That's a nice solution. I'm reminded of a short video I watched on the Lego factory. One segment of it discussed the machine that put the minifigs' heads on their bodies. There's a big hopper of bodies that get drawn up onto a belt and then a camera makes sure each body is facing the right direction before putting the head on.

What do they do with bodies that are facing backwards? Is there a little side channel that flips them around? Nope, they just get tossed back into the hopper to try again. It's effectively random which way they'll be facing when they get picked up, so they'll eventually get through.

I thought that was a nice illustration of keeping things simple and taking advantage of processes you already have, and seems similar in spirit to this.

That's exactly what I love about this whole project. It's an endless series of seemingly simple puzzles. Then you start solving them and they turn out to be much more complicated than you thought. Until you hit the solution and then it's simple again.

Now you've got me thinking of Frank Abagnale (from Catch Me If You Can). He forged checks where the computer-readable routing number written in magnetic ink didn't match the bank the check was supposedly from, which resulted in the checks cycling nonstop back and forth through the Federal Reserve's system. They only caught on to it because one of the checks went through so many times it started to fall apart and got flagged as unreadable.

Maybe there's some defective minifig body with a mechanical flaw that causes it to always get picked up facing backwards, that's spent years being picked up and rejected over and over.